The present invention relates to a three-dimensional shape and color detecting apparatus employed, for example, in a three-dimensional scanner, capable of detecting a three-dimensional shape of an object and the color thereof.
Conventionally, three-dimensional shape and color detecting apparatuses for detecting a three-dimensional shape of an object and the color thereof based on light reflected by the object have been known.
An example of such apparatuses is disclosed in Japanese Patent Provisional Publication P2001-145126A (published on May 25, 2001). In this publication, the apparatus includes a laser unit which sequentially emits red, green and blue laser beams toward an object, and receives the reflected beams with a CCD (Charge Coupled Device). Then, based on an image formed on the CCD, distances to various portions on the object are obtained, thereby detecting the three-dimensional shape of the object. Further, in this apparatus, for each of the three color beams, the reflected components are received with the CCD, and detects the color of the object.
Another method is known in which a point light source (such as flash light emitted by a strobe device) is used to illuminate an object and the color thereof is determined.
When a light source is located at a predetermined fixed position, however, it is difficult to detects the color of the entire object, as described below.
FIG. 14 schematically shows a structure of the conventional shape detecting apparatus.
In the structure shown in FIG. 14, a point light source P30 and a CCD camera P11 are arranged on the left-hand side (which will also be referred to a front side of the object) of an object P3 to be detected. A ray RB of light emitted by the point light source P30 and incident on a point B at a side surface of the object P3 has a relatively large incident angle (i.e., an angle xcex2 formed between the ray RB and a normal NLA to the surface of the object at a point where the ray strikes the object P3) in comparison with the incident angle xcex1 of the ray RA striking a point A located at the front side of the object P3. DB1 and DB2 denote intensity distributions of reflection components at the points A and B, respectively.
Therefore, the quantity of light of reflection components of the light from the points A and B incident on the CCD camera P11 are considerably different. In particular, the quantity of light of the component from the point B to the CCD camera is very small, and a color of the object at the point B cannot be detected accurately.
There is suggested another method, in which the color and shape of the object are measured at various angles, and then based on the thus obtained measurement data, the shape and color of the object is determined. In this method, however, stepwise color variation which does not exist in reality may appear in the entire three-dimensional image obtained in accordance with the above method. This problem will be described in detail below.
When the entire three-dimensional image of the object P3 is generated, firstly, as shown in FIG. 15A, the three-dimensional shape and color of the object P3 are detected from its front side. With this condition, an area AR1 is measured. Then, as shown in FIG. 15B, the object P3 is rotated by 90 degrees, and the three-dimensional shape and color are detected from the left side of the object. Then, an area AR2 is measured. Similarly, the detection is performed from the rear side and the right side of the object with rotating the object P3 by 180 degrees and 270 degrees, respectively. Then, the images thus obtained are synthesized to form a final image of the object P3 as shown in FIG. 16.
In the three-dimensional shape of the object P3 shown in FIG. 16, a left-hand side portion SLH of a line C represents an image when the object P3 is oriented as shown in FIG. 15A, and a right-hand side portion SRH of the line C represents an image when the object P3 is oriented as shown in FIG. 15B.
As aforementioned, in the conventional three-dimensional shape and color detecting apparatus, the color of a surface which faces aside the light source cannot be detected correctly. Therefore, when the object P3 is oriented as shown in FIG. 15A, the color of a portion in the vicinity of the line C cannot be detected correctly. Since the image of the left-hand side portion of the line C is detected when the object P3 is oriented as shown in FIG. 15A, the color CLH of this portion of the finally obtained three-dimensional image (shown in FIG. 16) is different from the true color of this portion of the object P3.
On the other hand, the color CRH of the right-hand side area of the line C is detected when the object P3 is oriented as shown in FIG. 15B. Therefore, it is expected that the color of the image of this portion of the three-dimensional image correctly represents the true color of this portion of the object P3.
As above, there is a step of color difference at the border line C.
The present invention is advantageous in that a three-dimensional shape and color detecting apparatus capable of detecting the color of the object over the entire area of the three-dimensional shape can be provided.
According to an aspect of the invention, there is provided a three-dimensional shape and color detecting apparatus that detects a three-dimensional shape of an object and a color thereof, which is provided with an illuminating system that emits light to illuminate the object, and a light receiving device that receives a reflected component of the light from the object. In this structure, the illuminating system is configured to emit the light from a surface having a predetermined area to the object.
Optionally, the light receiving device may include a two-dimensional image capturing element.
Further optionally, the surface emitting the light may include, when viewed from the object side, portions facing each other with the light receiving device located therebetween.
In an embodiment, a solid angle formed by the predetermined area with respect to a center of the object is one steradian or larger.
Preferably, the light illuminating the object may include diffused light. Optionally, the diffused light is white light.
Further optionally, the illuminating system may include a light source, and a light diffusing member that diffuses the light emitted by the light source.
In this case, the light source may be arranged, when viewed from the object side, behind the light diffusing member. Alternatively or optionally, the light source may be arranged, when viewed from the object side, on a near side of the light diffusing member. In an embodiment, the light source includes a plurality of linear fluorescent lamps.
The detecting apparatus may include a rotary table on which the object is held.
Yet optionally, the detecting apparatus may include a light shielding member that prevents ambient light from being incident on the object.
Still further, the detecting apparatus may be provided with a slit light beam emitting system that emits a slit beam to the object, and a three-dimensional shape detecting system that detects the three-dimensional shape of the object in accordance with an image of an object at a portion illuminated by the slit beam.
Optionally, the light receiving device receives the image of the illuminated portion of the object.
Further optionally, light emission of the illuminating system is inhibited when the three-dimensional shape of the object is measured, and emission of the slit beam of the slit light beam emitting system is inhibited when the color of the object is measured.
The detecting apparatus may further include a scanning system that moves the slit beam emitting system and the light receiving device relative to the object in a direction perpendicular to an extending direction of the slit beam so as to scan the object with the slit beam.
According to another aspect of the invention, there is provided with a three-dimensional shape and color detecting apparatus that detects a three-dimensional shape of an object and a color thereof, which is provided with a slit beam emitting system that emits a slit beam to the object, cross section of the slit beam being extending in a predetermined direction, an illuminating system that emits illuminating light having substantially an even intensity distribution toward entire area of the object, and a light receiving device that receives an illuminated portion of the object. In this configuration, when the three-dimensional shape of the object is detected, the slit beam is emitted to the object and the reflected beam is received by the light receiving device, and when the color of the object is detected, the illuminating light is emitted to the object and the reflected beam is received by the light receiving device.
Optionally, the illuminating system may include a surface light source. Further, a solid angle formed by an area of the surface light source with respect to a center of the object may be at least one steradian.
Further optionally, the detecting apparatus may include a scanning system that moves the slit beam emitting system and the light receiving device relative to the object in a direction perpendicular to an extending direction of the slit beam so as to scan the object with the slit beam.
Furthermore, the apparatus is provide with a controller that controls the illuminating system and the slit beam emitting system to operate. The controller inhibits light emission of the illuminating system when the three-dimensional shape of the object is measured, and inhibits emission of the slit beam of the slit light beam emitting system when the color of the object is measured.